This invention relates to a cryogenic envelope for a transmission line. In this respect, a preferred embodiment of the invention will be described in connection with a cryogenic envelope for a flexible superconducting power transmission line.
In order to be commercially attractive, superconductive power transmission lines must have low thermal losses and high reliability. Consequently, it is an object of this invention to provide a transmission line having a cryogenic envelope that is both reliable and results in a low heat-leak structure.
In one embodiment of the invention it is contemplated that a flexible superconductor cable be pulled through an insulating envelope. Hence, the structure of that embodiment includes means whereby the superconductor cable has little tendency to be snagged as it is pulled through the envelope.
Another problem with existing transmission lines is that they tend to buckle or break when either being warmed up for repairs or cooled down upon being placed into operation. Consequently, one of the embodiments about to be described includes structure for permitting various components of the envelope to suitably expand and contract during warm up or cooldown.